The present invention relates to the field of packet communications. More specifically, in one embodiment the invention provides an efficient communications network for client-server networks with large numbers of clients.
A client-server network is a network where one or more servers are coupled to one or more clients over a communications channel. Typically, each server and each client is assigned an address so that each can determine which network messages are directed to it. While such a system may have only one server, it typically has many clients. A server object is one which waits for a request from a client object and then performs some service in response to the client request. A client is an object that makes the request. The designation of a particular object (computer hardware and/or software process) as a “server” object or a “client” object is not fixed. Thus, a given object can be a server for some services and a client of other services.
A typical computer network has one or more file and print servers with a number of clients, where the clients are the desktop computers or workstations of the computer users, all coupled to a high-speed network cable. Client-server communications in such a network are easily handled for several reasons. When clients are not all communicating with the server at once the server need not be designed to handle all the clients at one time. Another reason is that the network traffic is much less than the network capacity furthermore, the clients in a typical computer network need not necessarily be communicating in real-time with the server. However, where many client machines or processes are communicating with each other in real-time through the server, several problems arise.
For example, where a client-server system is used for real-time exchange of information, such as a distributed virtual reality network where users at client machines visually and aurally interact with other users at other client machines, communication is much more difficult, especially where the information is high-bandwidth data such as audio streams, graphic images and image streams. One application of such a client-server system is for game playing, where the positions and actions of each user need to be communicated between all the players to inform each client of the state changes (position, actions, etc.) which occurred at the other clients. The server might maintain global state information and serve as a data server for the clients as they request visual, program and other data as the game progresses.
Some game systems use a peer-to-peer architecture. In a peer-to-peer architecture, a copy of the data which is common to all clients is kept by the client and information which needs to pass between clients is broadcast over the network. This limits the number of clients which can be connected to the network, because the number of messages passing between clients is on the order of the square of the number of clients. With true broadcasting, one message is sent and all clients listen for it, but not all network topologies can handle broadcasts. Where less than all the clients are participating in a game, for example, messages cannot be broadcast because there are clients which should not be receiving the broadcast message. Instead, the broadcast between the players is handled by generating one message to each player client.
This architecture is further limited where the network is not a dedicated network, but is an open network, such as the Internet. As used herein, the term “Internet” refers to the global inter-network of networks which communicates primarily using packets sent according to TCP/IP (Transport Control Protocol/Internet Protocol) standards well known in the art of computer intercommunication. With Internet communications, true broadcasting is not even possible because the network's extent is not known or fixed. Thus, messages to all players must be sent as separate messages. An additional problem with Internet communications is that packet delivery is not guaranteed nor is it even as reliable as a dedicated network.
Therefore, what is needed is an efficient system for communication between many client systems over dedicated or open networks to provide graphical interaction between users operating the client systems.